1. Field of the Invention
This invention relates to seals between adjacent relatively moveable members and, more particularly, to a sprung seal usable in a gas turbine engine exhaust nozzle.
2. Description of Related Art
Variable area and vectoring exhaust nozzles of aircraft gas turbine engines for aircraft typically employ two dimensional (2D) nozzles having relatively stationary sidewalls movable flaps. The sidewalls and flaps define, at least in part, boundaries of a hot exhaust flowpath in the nozzle and employ seals between them to contain hot pressurized exhaust gases within the exhaust flowpath and prevent them from leaking out of the nozzle. During the nozzle's operation, the flaps are moved, typically rotated about an axis, and the flaps slide relative to the sidewalls. Space between the moveable flaps and the stationary sidewalls provides a leakage path for relatively high pressure gases in the exhaust flowpath. A major concern in the design of such exhaust systems, therefore, is the control of leakage through a space or gap between the two relatively slidable members. Thus, seals are provided to reduce or substantially eliminate leakage between the members or flaps and the sidewalls.
Exemplary types of exhaust seals that have been used in the past are elastic leaf seals and hinge leaf seals. Elastic leaf seals consist of a generally “U”, “S”, or otherwise shaped member which is fastened on one side to one of the members to be sealed and is in rubbing contact on its other side to the other member. This seal may be spring loaded so that as the two members move apart, it maintains contact therebetween. The seals are designed to be strong enough to withstand the relatively high pressure of the exhaust flow gases and to be flexible enough to expand and contract with variations in the gap. Hinge leaf seals generally include two flat sheets which pivot from a common hinge point. One of the sheets is attached to one of the members to be sealed and the other sheet is in rubbing contact with the other member.
New modern nozzle designs call for sealing between relatively movable members which undergo large relative movement and at least one of the members may have a contoured sealing surface. Thus, it is highly desirable to have an effective seal for sealing between relatively movable members which undergo large relative movement, one of which has a contoured sealing surface.